A FALCON FLIES by Wilbur Smith

In 1860, a man and woman approach the coast of Africa aboard a swift clipper--in the command of an American who knows no law. Robyn Ballantyne and her brother Morris have waited years for this moment: to return to Africa, to search for their missionary father who had disappeared somewhere in the wilderness.

Traveling north from Cape Town, they follow a map left by a madman--into an uncharted world of waterfalls and jungle, teeming wildlife, murderous disease, and the ghastly ruins of an astounding city. 
 
Uncovering their father's trail, Robyn and her brother are in the midst of a slave trade that pours out of Africa like a bloody wound. Now, to survive what they have found, they must make their separate ways out--through pitched battles on land and on sea…and through the pride, passions and fury of their hearts…